A search is under way for a teenager missing on a school trip to the rain forests of Tena in eastern Ecuador.
Civil Defence Force units are searching for Aaron Goss
Aaron Goss, 17, of Rushden, Northants, was on an Adventureworks trip with 17 other students from Wollaston School.
A search of the area took place after he went missing on Wednesday while some members of the group were swimming.
A spokesman for the group said one of the leaders told them to get out of the water after seeing a splash and it was then found that Aaron was missing.
The team of students and two teachers were led by two professional leaders from Adventureworks, supported throughout the three-week expedition by local Ecuadorian guides.
In a statement the company said a dug-out canoe had been used to ferry the group, five at a time, across the river to a good swimming point on the opposite bank.
Two leaders, one of them a trained lifeguard, entered the water first to check for hazards, it said.
"While some of the students were swimming, others waited on the bank. One of the Adventureworks leaders noticed a splash at the edge of his vision.
"As a precaution, he immediately told everyone to get out of the water, and the leaders conducted a head-count. One student was missing," the company said.
An initial search of the rivers and banks in the area was carried out by teachers and the children before Ecuador's Civil Defence Force was called in.
The Foreign and Commonwealth Office (FCO) told BBC News the Civil Defence Force would remain in the area to help with the search effort.
Northamptonshire Police have appointed a family liaison officer to help and advise Aaron's family.
Deputy head of Wollaston Secondary School, Anne Murdoch said: "Everything is currently being done to help find a missing teenager and our thoughts are with his family and friends at this very worrying time."
Northamptonshire County Council director for children and young people, Andrew Sortwell, said: "This is an incredibly worrying time.
"We are now working with the school, Northamptonshire Police and the Foreign Office to ensure all is being done to offer all the support possible."
Adventureworks said: "Our thought's are with the family at this worrying time.
"The rest of the group are safe and will return to Quito and fly to the UK over the next few days."
The company also said it will conduct a full investigation into the incident.